KR100569079B1 - Control method of preventing engine stall for continuously variable valve timing system in vehicle - Google Patents

Abstract

To provide a control method for preventing the start-up and shutdown of a combustion variable valve timing system vehicle to prevent the engine from turning off in the event of a failure due to the ground ground of the CVVT control line;

A method of diagnosing electrical failure of a CVVT control line in a continuously variable valve timing system vehicle,

The fault alarm is issued only when the CVVT control line is open (disconnected state), the battery ground of the CVVT control line, or the ground ground of the CVVT control line is satisfied, but the engine is grounded when the CVVT control line is grounded. Provided is a method of controlling a vehicle to prevent starting off of a continuous variable valve timing system that enables a failure alarm after a limp home control is performed to prevent starting.

Rim groove control. CVVT control line.

Description

Continuously variable valve timing system How to control the vehicle's engine start-off {CONTROL METHOD OF PREVENTING ENGINE STALL FOR CONTINUOUSLY VARIABLE VALVE TIMING SYSTEM IN VEHICLE}

1 is a block diagram of a valve opening and closing time variable apparatus to which the present invention is applied.

2 is an operational flowchart of a control method according to the present invention;

3 is an operational flowchart of a first embodiment of lymphatic home control applied to the control method of the present invention;

4 is an operational flowchart of a second embodiment of lymphatic home control applied to the control method of the present invention;

5 is a flowchart of a conventional operation control.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for preventing starting off in a continuously variable valve timing system (hereinafter referred to as CVVT) vehicle, and more particularly, to start an engine in the event of a failure due to ground ground of a CVVT control line. The present invention relates to a control method of preventing the start-off of a combustion variable valve timing system vehicle, which prevents the engine from turning off.

The intake / exhaust valve in the internal combustion engine is configured to be opened and closed by being driven by a cam formed on the camshaft which is connected to the crankshaft and the chain or timing belt and rotates together.

And, in order to improve the output of the engine, it is preferable to set the opening and closing speed of the valve and its leaf amount to be large to increase the area where the valve is opened, so that a large amount of air is sucked into the combustion chamber.

However, excessively large valve speeds and lift amounts can cause the valve to collide with the valve seat or cause the movement of the valve to be unrelated to the profile of the cam, resulting in increased noise and damage to the valve.

Accordingly, in recent years, variable intake and exhaust valves have been proposed, which can improve the rotational output and fuel efficiency by varying the opening / closing time of the valve according to the operating conditions of the engine, and are widely applied to actual vehicles.

As an example, as shown in FIG. 1, a VVT unit (Variable Valve Timing Unit) 6 is disposed inside the sprocket 4 formed at the front end of the intake camshaft 2, and an oil flow is provided in the VVT unit 6 thereof. A control valve (Oil-Flow Control Valve) 8 is included, and the oil flow control valve 8 is configured to change the flow path of the hydraulic pressure supplied from the oil pump 10 to the VVT unit 6. .

The electronic control unit (ECU) includes a crank position sensor 12, a cam position sensor 14, an engine RPM sensor 16, a throttle position sensor 18, a vehicle speed sensor 20, a water temperature sensor 22, and the like. The overlap of the valve is controlled by calculating a duty value according to a signal input from various sensors including the wire, and a wire for transmitting the duty control value to the oil flow control valve 8 is called a CVVT control line. .

The failure of the CVVT control line as described above can be exemplified in the following three cases from an electrical point of view.

First, an example is a case in which the battery is grounded to the CVVT control line so that the control value transmitted to the oil flow control valve 8 becomes the voltage of the battery.

In this case, the potential difference is zero and the D duty control value is always zero, and the CVVT control is always at maximum retardation. At that time, the engine cannot perform accurate control according to the driving situation. There is a problem that does not occur, but the engine combustion itself does not cause a large crowd does not cause a special problem such as engine off.

Of course, the ECU notifies the driver of the fault condition to troubleshoot the fault diagnosis that informs the fault condition so that maintenance can be performed.

Second, the CVVT control line may be disconnected. In this case, the duty control signal is not transmitted at all, and the CVVT is controlled to the maximum perceived state as described above. It does not cause any serious problems and will inform the driver of the fault condition.

Third, there is a case where the CVVT control line is grounded. In this case, the potential difference always occurs, so that the 100% duty control value is always controlled by CVVT, so that the CVVT control is controlled at the maximum advance state. As the overlap is maximized, the combustion state of the engine becomes unstable, and the engine may be turned off due to misfire.

Considering this point, a method of diagnosing all control line failures with the conventional oil flow control valve 8 and all oil flow control valves 8 will be described. As shown in FIG. It is determined whether or not (disconnected state) (S300).

When it is determined in the step S300 that the open state is a fault alarm (S310), the failure diagnosis is terminated, and when it is determined that the open state is not determined in the step S300, it is determined whether the duty control value is smaller than the minimum error value (S320). .

If it is determined in step S320 that the duty control value is smaller than the minimum error value, since the CVVT control line is grounded to the battery, after the failure alarm S310, the failure diagnosis is terminated, and the duty control value is the minimum error value in step S320. If it is determined that it is larger than normal, it is determined whether the duty control value is smaller than the maximum error value (S330).

If it is determined in step S330 that the duty control value is smaller than the maximum error value, since the CVVT control line is grounded to ground, after a failure alarm (S310), the failure diagnosis is terminated, and the duty control value is an error in step S330. If it is determined that it is larger than the maximum value, it is normal, and thus the failure diagnosis is finished while performing the normal control (S340).

However, in the above fault diagnosis method, even if the CVVT control line is grounded to the ground, the driver may only warn the driver and fail to take a countermeasure, thereby causing the engine to turn off.

As described above, when the start-off phenomenon occurs while driving the vehicle, braking becomes difficult and problems occur in steering wheel operation, which may cause a large accident during high-speed driving.

Therefore, the present invention has been invented to solve the problems of the prior art as described above, the object of the present invention is to prevent the engine starting to be turned off in the event of a failure due to the ground ground of the CVVT control line to ensure safe operation A combustion control valve timing system provides a control method of preventing starting of a vehicle.

In order to realize this, the present invention provides a method for diagnosing electrical failure of a CVVT control line in a continuously variable valve timing system vehicle.

The fault alarm is issued only if the condition of the open (disconnected state) of the CVVT control line, the battery ground of the CVVT control line, or the ground ground of the CVVT control line is satisfied.

Provided is a control method of preventing start-off of a continuous variable valve timing system vehicle, which performs a failure alarm after performing a limp home control so that an engine start does not turn off when the ground of the CVVT control line is grounded.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described in detail.

1 is a perspective view showing an example of a variable valve opening and closing device applied to the present invention, as described above, VVT unit (Variable Valve Timing Unit, 6) inside the sprocket 4 formed in the front end of the intake camshaft (2) ), And the VVT unit 6 thereof includes an oil flow control valve (8), and the oil flow control valve (8) is connected from the oil pump (10) to the VVT unit (6). It is configured to change the flow path of the hydraulic pressure supplied to.

The electronic control unit (ECU) includes a crank position sensor 12, a cam position sensor 14, an engine RPM sensor 16, a throttle position sensor 18, a vehicle speed sensor 20, a water temperature sensor 22, and the like. The overlap value of the valve is controlled by calculating a duty value according to a signal input from various sensors included.

Looking at the failure diagnosis method according to the present invention in this control process, the basic control is the same as before.

That is, as shown in FIG. 2, the diagnosis is started to first determine whether the control line is in an open state (disconnected state) (S100).

If it is determined in the step S100 that the open state is a fault alarm (S110), the failure diagnosis is terminated, and if it is determined that the open state is not in the step S100, it is determined whether the duty control value is smaller than the minimum error value (S120). .

If it is determined in step S120 that the duty control value is smaller than the minimum error value, since the CVVT control line is grounded to the battery, after the failure alarm (S110), the failure diagnosis is terminated, and the duty control value is the minimum error value in step S120. If it is determined that it is larger than normal, it is determined whether the duty control value is smaller than the maximum error value (S130).

If it is determined in step S130 that the duty control value is less than the maximum error value, the CVVT control line is grounded, so after performing a failure alarm (S110), the failure diagnosis is terminated, and the duty control value is an error in step S130 If it is determined that it is larger than the maximum value, it is normal, and thus the failure diagnosis is finished while performing the normal control (S140).

In the fault diagnosis process as described above, the present invention satisfies the conditions in step S130, and when it is determined that the fault is not immediately performed a fault alarm (S110), after performing the lymph groove control (S150), a fault alarm (S110) ) Was performed.

The lymph groove control (S150) may be performed in two embodiments of a method of changing a target torque and a method of changing a target engine speed. A method of changing the target torque is illustrated in FIG. 3.

When it is determined in the step S130 that the CVVT control line is grounded to the ground, the engine speed (N) is selected and the basic target engine speed (N_SP) according to the engine operating state is set (S151a).

The basic target engine speed (N_SP) is to be set based on the data mapped to the TCU according to the engine operating state. When the step S151a is completed, the lymphatic home torque is set to the required lymphatic home torque (TQ_REQ_LIMP_HOME). After the calculation (S151b), the torque TQ_REQ_dN for the rotation speed change amount dN due to the basic target rotation speed N_SP and the engine rotation speed N is set to the basic torque value TQ_REQ_dn and the required lymphatic groove torque TQ_REQ_LIMP_HOME. It calculates with the sum (S152c).

After the duty control value of the idle speed actuator ISA is calculated based on the torque TQ_REQ_dN for the rotation speed change calculated in step S152c (S151d), the engine speed is controlled using the duty control value (S152e). ), The failure alarm (S110) is performed.

In addition, referring to the method of changing the target engine speed, as shown in FIG. 4, if it is determined in step S130 that the CVVT control line is grounded to the ground, the engine speed N is selected and the engine operating state. The basic target engine speed N_SP is set according to step S152a.

The basic target engine speed (N_SP) is set based on the data mapped to the TCU according to the engine operating state. When the step S152a is completed, the required target engine speed (N_SP) is required to stabilize the operation of the current engine. After calculating the number TN_SP by adding the basic target engine speed N_SP to 300 RPM (S152b), the rotation speed change amount dN for the difference between the required target engine speed TN_SP and the engine speed N ) Is calculated (S152c).

Calculating the required target engine speed (TN_SP) by adding 300 RPM to the basic target engine speed (N_SP) above is to raise the target value by about 300 RPM above the reference value in order to prevent engine starting off due to misfire. The numerical value thereof is not limited to 300 RPM.

After selecting the target torque TQ_REQ_dN based on the rotation speed change amount dN (S152d), the duty control value of the idle speed actuator ISA is based on the target torque TQ_REQ_dN for the rotation speed change amount thereof. (S151e), the engine speed is controlled by this duty control value (S152f), and a failure alarm (S110) is performed.

In other words, the present invention is to prevent the engine from being turned off due to misfire due to the ground ground of the CVVT control line. As a solution to this, the torque is sufficiently increased so as not to turn off the engine or the engine speed is controlled to increase the engine speed. I would have to.

As described above, according to the present invention, in the vehicle to which the continuous variable valve timing system is applied, the engine starting is prevented from turning off due to misfire due to the maximum advance control of the valve overlap in case of failure due to the ground ground of the CVVT control line. It is an invention that can promote safe operation.

Claims (4)

A method of diagnosing electrical failure of a CVVT control line in a continuously variable valve timing system vehicle, The fault alarm is issued only if the condition of the open (disconnected state) of the CVVT control line, the battery ground of the CVVT control line, or the ground ground of the CVVT control line is satisfied. And a failure alarm after the lymph groove control is performed so that the engine start does not turn off when the ground of the CVVT control line is grounded. delete The method of claim 1, wherein the lymph groove control is performed by changing the engine target torque, If it is determined that the CVVT control line is grounded to ground, a first step of selecting an engine speed N and setting a basic target engine speed N_SP according to the engine operating state; After the execution of the first step, the lymph groove torque is calculated as the required lymph groove torque (TQ_REQ_LIMP_HOME) value, and then the torque with respect to the rotation speed change amount dN by the basic target rotation speed N_SP and the engine rotation speed N. A second step of calculating (TQ_REQ_dN) as the sum of the basic torque value TQ_REQ_dn and the required lymphatic home torque TQ_REQ_LIMP_HOME; The duty control value of the idle speed actuator ISA is calculated on the basis of the torque TQ_REQ_dN with respect to the rotation speed change amount calculated in the second step, and the engine speed is controlled using this duty control value, and then a failure alarm is performed. The control method of the start-off protection of the continuous variable valve timing system vehicle, characterized in that consisting of a third step. The method of claim 1, wherein the lymph groove control is performed by changing the target engine speed, If it is determined that the CVVT control line is grounded to ground, a first step of selecting an engine speed N and setting a basic target engine speed N_SP according to the engine operating state; After the execution of the first step, the required target engine speed TN_SP is calculated as the basic target engine speed N_SP plus 300 RPM, and then the required target engine speed TN_SP is added to the required target engine speed TN_SP and the engine speed N. A second step of calculating an amount of rotation change dN for the difference; After selecting the target torque TQ_REQ_dN based on the rotation speed change amount dN calculated in the second step, the duty control of the idle speed actuator ISA is based on the target torque TQ_REQ_dN for the rotation speed change amount thereof. And a third step of calculating a value and controlling the engine speed with the duty control value and then performing a failure alarm.

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